1. Field of the Invention
The present invention relates to an ink cartridge comprising an accommodating chamber in which a porous member impregnated with ink is held, an ink supply port provided in a wall portion, which is to be connected with an outside head, and an ink storing chamber between the accommodating chamber and the wall portion, and more particularly to an ink cartridge in which an ink flow passage is formed in a curve from a through hole connecting the accommodating chamber and the ink storing chamber to the ink supply port so that air bubbles existing in the ink can be released from the ink, to stop the air bubbles from entering through the ink supply port into the outside head, thereby to prevent a deterioration in printing quality, and prevent the outside head from becoming unworkable.
2. Description of Related Art
An ink cartridge to be used in an ink jet printer holds a porous member impregnated with ink in an accommodating chamber in a cartridge case. The ink cartridge supplies ink through an ink supply port formed in a wall of the cartridge case to a recording head side in the outside ink jet printer and, simultaneously, introduces the atmospheric air into the accommodating chamber through an air communication port formed in another wall of the cartridge case, which is positioned away from the position of the ink supply port.
The air introduced through the air communication port replaces the ink impregnated in the porous member, causing the ink to be discharged little by little through the ink supply port, which achieves a smooth ink supply to the ink jet head.
When ink is poured to the porous member held in the cartridge case, it is general to suck the air out of the cartridge case and then pour ink through the ink supply port or the air communication port of the cartridge case into the porous member, absorbing the ink.
However, the inside of the cartridge case can not be made in a complete vacuum even if the air is sucked out of the cartridge case, which may cause a possibility that the air bubbles remaining in the porous member is left as it is in the poured ink. The air bubbles will stably exist in the ink in the porous member. There is a possibility that the air bubbles are sucked into the recording head during a printing operation although enough ink remains in the ink cartridge, deteriorating a printing quality or preventing a printing operation by the recording head.
To solve the above problems, there is known an ink cartridge wherein a liquid chamber (an ink storing chamber) is formed on an ink flow passage through which ink flows from a porous member to an ink supply port in order to prevent the air bubbles from entering through the ink supply port into a recording head side, which is disclosed, for example, in a Japanese Patent Application Laid-open No. 6-238908.
However, in such the ink cartridge, the ink flow passage is formed in a substantially straight form between the through hole which connects the accommodating chamber with the ink storing chamber and the ink supply port. The ink flow passage merely goes straight through the ink storing chamber, accordingly. In this case, the air bubbles remaining in the ink flow can not be effectively removed therefrom while the ink flows along the ink flow passage between the through hole and the ink supply port, thus allowing the air bubbles to enter into the recording head, resulting in a deterioration in printing quality and causing the unworkableness of the recording head.